P: Undo button toolbar isn't appearing

Just a quick question here. For those of you who saw this and then saw it disappear, do you have a tablet attached?

I can see them on Windows but not Mac. I will log a bug for it. 

I'd love to see a screenshot of these undo buttons, as I've never seen them on the desktop. They are on mobile though.

I have the same issue.  I am a new user and the undo/redo buttons were there for the first few days, then they disappeared.  Please help.

Lightroom version: 3.2 [ 20200204-0604-bc5e360 ] (Feb  4 2020)
NGL Version: 1.14.0.16
Operating system: Windows 10
OS Version: 10.0 [18363]
Application architecture: x64
System architecture: x64
Computer model: Dell Inc. Inspiron 7373 / Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
Logical processor count: 8
Processor speed: 1.8 GHz
Built-in memory: 8026.1 MB
Real memory available to Lightroom: 8026.1 MB
Real memory used by Lightroom: 1708.3 MB (21.2%)
Virtual memory used by Lightroom: 1831.4 MB
Memory cache size: 1609.3 MB
Internal Camera Raw version: 12.2 [ 385 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 549MB / 4013MB (13%)
Camera Raw real memory: 550MB / 8026MB (6%)
System DPI setting: 96 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1080, 2) 1920x1080
Input types: Multitouch: No, Integrated touch: No, Integrated pen: Yes, External touch: No, External pen: No, Keyboard: Yes

Graphics Processor Info: DirectX: Intel(R) UHD Graphics 620 (23.20.16.4973)
Graphics Processor Detail: loaded: Yes, supported: Yes, compute: No, init: I2_GPU2, hard: fail_cached_sanity_test, soft: not_checked, wl: No, bl: No
OS Media Capability: true

Application Folder: C:\Program Files\Adobe\Adobe Lightroom CC
Settings Folder: C:\Users\claud\AppData\Roaming\Adobe\Lightroom CC
Library Folder: C:\Users\claud\AppData\Local\Adobe\Lightroom CC\Data

Also disappeared, pls help.

Lightroom version: 2.4 [ 20190802-0905-45e6444 ] (Aug  2 2019)
NGL Version: 1.10.0.4
Operating system: Windows 10
OS Version: 10.0 [18362]
Application architecture: x64
System architecture: x64
Computer model: Gigabyte Technology Co., Ltd. Z170X-UD5 / Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
Logical processor count: 8
Processor speed: 4.0 GHz
Built-in memory: 16337.9 MB
Real memory available to Lightroom: 16337.9 MB
Real memory used by Lightroom: 1450.2 MB (8.8%)
Virtual memory used by Lightroom: 2194.5 MB
Memory cache size: 1828.4 MB
Internal Camera Raw version: 11.4 [ 274 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 825MB / 8168MB (10%)
Camera Raw real memory: 826MB / 16337MB (5%)
System DPI setting: 96 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1080
Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No

Graphics Processor Info: DirectX: NVIDIA GeForce GTX 970 (26.21.14.3602) - 4 GB

Jean,

Please go to Help>System Info... and get us the installed Lightroom Version Number. 
Additionally, we will need your OS Version Number.